An authentic (style) school mystery is born here! At Kazama-kun's invitation, Shinnosuke and his friends decide to enroll in the super elite boarding school ``Private Tenka Unification Kasukabe Gakuen'', commonly known as Tenkasu Gakuen, for a week! Has Kazama-kun turned into an idiot after getting caught up in the mysterious incidents that occur frequently at the school? ! In order to uncover the truth of the incident, Shinnosuke and his friends set up the "Kasukabe Detective Club"! What did Shinnosuke and his friends discover through their stray deductions?
Shinnosuke - Osiri, sealed!! In order to restore To-chan-ka-chan, who was turned into a child by the alien Shiriri's mysterious beam, he hides the alien Shiriri in Osiri and travels across Japan!